(488g) Electrolytic Air Dehumidification Via Reverse Fuel Cells with Sulfonated Pentablock Terpolymer Membranes

Electrolytic air dehumidification utilizing reverse fuel cells containing solid-state proton exchange membranes (PEMs) as the electrolyte has the advantages of compact design and low operating voltage compared to conventional dehumidification approaches with refrigerants or desiccants. However, the commonly used Nafion membrane as a PEM has several disadvantages, including high production and disposal costs due to its fluorinated chemistry. In this work, a new type of low-cost hydrocarbon-based sulfonated pentablock terpolymer membrane (Nexarâ„¢, Kraton Corporation) was evaluated in a reverse fuel cell for electrolytic air dehumidification. Nexar conjoins the orthogonal properties of high ion conductivity and robust mechanical strength in a nanostructured morphology. Membrane electrode assemblies (MEAs) of Nexar membranes at various ion exchange capacities (1.0 and 2.6 meq/g) were fabricated, evaluated, and compared with the industrial benchmark Nafion (0.9 meq/g) MEA. Water vapor transmission rate (WVTR), water removal energy efficiency, polarization and impedance characteristics were investigated at 50°C under different controlled environmental humidity (wet side = 100% RH, dry side = 10% or 50% RH) and voltage directions (counter/co-natural gradient). Compared to Nafion MEAs, Nexar MEAs with a similar IEC showed higher water removal energy efficiency, while Nexar MEAs with a higher IEC showed higher voltage-driven WVTR, but the water removal efficiency was compromised due to higher energy consumption. This study offers a comprehensive evaluation of low-cost Nexar as a promising PEM alternative to high-cost Nafion in electrolytic air dehumidification.